Engine Loping

[rdarrin]

Hey everyone, im new to jeepz... anyways, i have a 1998 jeep wrangler, 4.0 6cyl. im currently working on.. it has about 97,000 on it. For the past 2 years it has been running great up until about 2 weeks ago. the problem starts a couple minutes after starting it, the engine will start to lope or tries to cut out. when i give it gas it does not respond except by occasionally backfiring. if i try and move it while it is doing this, it just bucks. the engine has never completely died.. after a minute of screwing up it runs fine except it sounds like it is missing while idiling.. i checked all of the plugs and they had normal coloration, but i replaced them anyways.. the plug wires are good, replaced the distributor cap and rotor, cadalydic convertor to tailpipe were replaced about 6 months ago, replaced the air filter. i had the computer read to see if there were any codes, and there were none.. there is no check engine light except for the initial startup then it goes away like normal.. im not really sure where to go from here, i did kill the battery a couple of weeks ago by leaving the lights on, but had it recharged and seems to hold a good voltage. im not sure if this may have affected the computer or not....

 

[rdarrin]

a little update.. i checked the ignition solonoid today by measuring resistance in the primary and secondary coil, it checked sat.... is it possible my problem is coming from a bad 02 sensor?? my aft one was replaced about six months ago when my cat. conv. was replaced... my forward one looks like it has been a while since it has been replace... i still do not have any computer codes or check engine light.... also as a strange side note, today when it happend my gear shift light came on telling me to up shift even though i was in neutral while it was happening...

 

[cerial]

no I would pull off the IAC and give it a quick cleaning(this is probably the issue) you can pull it and clean it with a rang and depress the plunger a couple of times it will give you a little boost just by getting the surface carbon off.

But really what you need to do is rent a tester and make good use of the diagnostic system you have.
But first
When you first start the jeep(or when it is does the thing/dies) it will most likely flash the code(like 4/5 numbers get the code give it to your jeep dealer and they can run it and tell you what it is. I did this with a fuel relay worked great.

This is the cheap route the other route is to rent a tester from autozone or like place (big deposit but you will get all of it back when you return the part)and plug it in use the book and you will get codes and a crossrefrence to tell you what is wrong.

 

[rdarrin]

well i pulled out the aic found it to be fouled up.. i replaced it, but i still have the same problem..